1. Field of the Invention
The present invention relates generally to an ultrasonic microscope apparatus for observing an object surface or internal conditions of an object by using an ultrasonic wave, and more particularly, relates to an ultrasonic microscope apparatus wherein brightness and contrast of an image are adjustable.
2. Description of the Related Art
FIG. 4 illustrates an ultrasonic microscope apparatus constructed such that brightness and contrast of an image are adjustable. A transmission trigger signal is transmitted from pulse controller 2 to transmission pulse generator 1. Transmission pulse generator 1 emits a transmission pulse signal. Transducer 3 converts a transmission signal transmitted from transmission pulse generator 1 into an ultrasonic wave and makes the wave enter at acoustic lens 4. Acoustic lens 4 converges the ultrasonic wave at a point of sample S (on the object surface or in the object). The space between acoustic lens 4 and sample S is filled with coupler liquid 5 which serves to propagate an ultrasonic wave.
The ultrasonic wave reflected at sample S is made to enter again acoustic lens 4 and transmitted to transducer 3. Transducer 3 converts the reflected ultrasonic wave into an electric echo signal. This echo signal is input to amplifier 6 for amplification. The amplified echo signal is input to gate circuit 7. Gate circuit 7 extracts only a necessary wave component such as the reflected wave component in the sample from the echo signal, on the basis of a gate signal given at predetermined intervals from gate signal emitting circuit 16. Each emission interval of the gate signal is controlled by a gate trigger signal supplied from pulse controller 2 to gate signal emitting circuit 16.
The component of the reflected wave extracted by gate circuit 7 is input to peak detector 8 and its peak value is detected. The detected signal which is output from peak detector 8 is input to brightness adjuster 9, and the intensity of the detection signal is raised to an optional level. Further, contrast adjuster 10 amplifies a signal from brightness adjuster 9 at an optional amplification factor and emits a brightness signal. This brightness signal is converted to a digital signal by A/D converter 11. These brightness adjuster 9, contrast adjuster 10, and A/D converter 11 constitute image processor 12.
The digital signal which is output from A/D converter 11 is input to digital scan converter 13 synchronous with the trigger signal from pulse controller 2 and stored thereafter. This signal is read out as an image signal from digital scan converter 13 and shown on display 14 as occasion requires.
Sample S is two-dimensionally scanned by x-y scanner 15 controlled by pulse controller 2, and digital scan converter 13 stores brightness data indicating the intensity of the reflective sample wave at given x-y (respective scanning positions) for sample S. Therefore, an ultrasonic image of sample S can be obtained by showing the brightness data obtained through the two-dimensional scanning on display 14.
However, the intensity of the reflective wave from sample S varies widely, depending on acoustic properties of sample S, and the obtained ultrasonic image may be blackened or whitened.
Because of this, in watching an ultrasonic image shown on the display, a skilled operator has manually controlled gains of brightness adjuster 9 and contrast adjuster 10 and has manually adjusted brightness and contrast.
In this way, in the ultrasonic microscope apparatus shown in FIG. 4, a skilled operator must manually adjust the brightness and contrast of an ultrasonic image in accordance with the acoustic properties of a sample and very troublesome operations are required.